Platelet-derived growth factor BB is reduced in endometrial endothelial cells of women with abnormal uterine bleeding-endometrial disorder.

RESEARCH QUESTION: What is the expression pattern of platelet-derived growth factor BB (PDGF-BB), and its receptors, across the menstrual cycle in healthy control women and those with abnormal uterine bleeding-endometrial disorder (AUB-E)? DESIGN: Immunohistochemical staining for PDGF-BB, platelet-derived growth factor receptor alpha (PDGFRα) and platelet-derived growth factor beta (PDGFRß) was performed in control and AUB-E endometrium from the proliferative, early, mid- and late secretory phases of the menstrual cycle (n = 5 each group). Control proliferative phase endometrium was cultured in PDGF-BB (0, 10 ng/ml) and vascular maturation assessed (n = 3). Endothelial cell to vascular smooth muscle cell (VSMC) association was assessed after treatment with PDGF-BB (0, 1, 10 ng/ml). Secretion of angiogenic growth factors by endothelial cells or VSMC was determined. RESULTS: Endothelial cell immunoreactivity for PDGF-BB was reduced in the mid and late secretory phases in AUB-E (P = 0.008). PDGFRα was also reduced in mid secretory phase endothelial cells, proliferative and early secretory phase glandular epithelium in AUB-E (P = 0.008). PDGFRß expression was not altered. Treatment of proliferative phase endometrium with PDGF-BB (10 ng/ml) reduced the percentage of vessels expressing contractile VSMC markers. PDGF-BB had no effect on angiogenic growth factor secretion by endothelial cells or VSMC in vitro and did not affect their association in an in-vitro endothelial cell-VSMC association assay. CONCLUSIONS: Reduced endothelial cell expression of PDGF-BB in the AUB-E endometrium may contribute to the reduced vascular maturation previously observed in these women.

Transforming Growth Factor (TGF) ß and Endometrial Vascular Maturation.

Appropriate growth and development of the endometrium across the menstrual cycle is key for a woman's quality of life and reproductive well-being. Recurrent pregnancy loss (RPL) and heavy menstrual bleeding (HMB) affect a significant proportion of the female population worldwide. These endometrial pathologies have a significant impact on a woman's quality of life as well as placing a high economic burden on a country's health service. An underlying cause for both conditions is unknown in approximately 50% of cases. Previous research has demonstrated that aberrant endometrial vascular maturation is associated with both RPL and HMB, where it is increased in RPL but reduced in HMB. TGFß1 is one of the key growth factors that regulate vascular maturation, by inducing phenotypic switching of vascular smooth muscle cells (VSMCs) from a synthetic phenotype to a more contractile one. Our previous data demonstrated an increase in TGFß1 in the endometrium of RPL, while others have shown a decrease in women with HMB. However, TGFß1 bioavailability is tightly controlled, and we therefore sought to perform an extensive immunohistochemical analysis of different components in the pathway in the endometrium of normal controls, women with HMB or RPL. In addition, two in vitro models were used to examine the role of TGFß1 in endometrial vascular maturation and endothelial cell (EC):VSMC association. Taken all together, the immunohistochemical data suggest a decrease in bioavailability, receptor binding capacity, and signaling in the endometrium of women with HMB compared with controls. In contrast, there is an increase in the bioavailability of active TGFß1 in the endometrium of women with RPL compared with controls. Endometrial explants cultured in TGFß1 had an increase in the number of vessels associated with contractile VSMC markers, although the total number of vessels did not increase. In addition, TGFß1 increased EC:VSMC association in an in vitro model. In conclusion, TGFß1 is a key regulator of endometrial vascular maturation and could be considered as a therapeutic target for women suffering from HMB and/or RPL.

Are we managing women with Recurrent Miscarriage appropriately? A snapshot survey of clinical practice within the United Kingdom.

The aim of this study was to evaluate clinicians' views of managing women with first-trimester Recurrent Miscarriage within the UK compared with RCOG guidance. An online survey of 150 Association of Early Pregnancy Units members was conducted using SurveyMonkey™. Analysis was limited to UK-based respondents (102). Of the three key investigations, 98% performed antiphospholipid antibodies (APA) screening, 93.1% performed karyotyping for subsequent miscarriages and 86.3% performed a pelvic ultrasound routinely. Other routine investigations included inherited thrombophilias (65.7%), thyroid function tests (51.9%), diabetes mellitus screening (35.3%), parental karyotyping (34.3%), androgen profile (25.5%), 3-D ultrasound (17.6%), hysteroscopy (12.7%), hysterosalpingogram (9.8%), Vitamin D (7.8%), peripheral natural killer cells (2.9%) and uterine natural killer cells (2.9%). APA-positive women were offered treatment by 97.1%; however, 23.5% routinely offered treatment for APA-negative women. Other treatments offered routinely included progesterone (27.5%) and metformin (1.9%). Most clinicians managed RM as recommended by RCOG, however we have highlighted considerable deviation from the RCOG guidelines.IMPACT STATEMENTWhat is already known on this subject? Recurrent miscarriage (RM) can cause significant distress to women and their partners prompting referrals for investigation and management of this condition. Although UK national clinical guidance exists published by RCOG, the adherence to the guidance in clinical practice is not known.What do the results of this study add? This study shows that most clinicians performed investigations recommended by RCOG when managing women with RM. However, we have highlighted considerable variation of practice; many additional investigations were routinely performed and a quarter of clinicians offered treatments outside the RCOG guidance.What are the implications of these findings for clinical practice and/or further research? This paper demonstrates considerable variation of practice across the UK. Clinical practice may continue to vary whilst there are separate guidelines available from different professional organisations worldwide. Collaboration to produce a general consensus could reduce the variation in the care that these women receive.

Transient loss of endothelial cells in human spiral artery remodelling during early pregnancy: Challenging the dogma.

Spiral artery (SpA) remodelling is essential for a successful pregnancy and is best described by its morphological features; vascular smooth muscle cell separation and loss, vessel dilatation, and invasion by extravillous trophoblast cells (EVT). Current opinion holds that EVT fully replace the endothelial cells (EC) of the SpA and take on EC-like characteristics. Placental bed biopsies (6-20 weeks gestation) were immunostained for EC and EVT, showing transient loss of EC. In vessels containing an endovascular EVT plug (n = 28) 77.6 ± 19.3% of the lumen was covered by EC while in vessels without endovascular EVT (n = 100) it was 100 ± 0%.

Predictive value of cervical cytokine, antimicrobial and microflora levels for pre-term birth in high-risk women.

Spontaneous preterm birth (sPTB, delivery <37 weeks gestation), accounts for approximately 10% of births worldwide; the aetiology is multifactorial with intra-amniotic infection being one contributing factor. This study aimed to determine whether asymptomatic women with a history of sPTB or cervical surgery have altered levels of inflammatory/antimicrobial mediators and/or microflora within cervical fluid at 22-24 weeks gestation. External cervical fluid was collected from women with history of previous sPTB and/or cervical surgery at 22-24 weeks gestation (n = 135). Cytokine and antimicrobial peptides were measured on a multiplex platform or by ELISA. qPCR was performed for detection of 7 potentially pathogenic bacterial species. IL-8 and IL-1ß levels were lower in women who delivered preterm compared to those who delivered at term (IL-8 P = 0.02; IL-1ß P = 0.04). There were no differences in elafin or human beta defensin-1 protein levels between the two groups. Multiple bacterial species were detected in a higher proportion of women who delivered preterm than in those who delivered at term (P = 0.005). Cervical fluid IL-8 and IL-1ß and microflora have the potential to be used as biomarkers to predict sPTB in high risk women.

Uterine natural killer cells: Time for a re-appraisal?

The presence of unusual natural killer cells in human endometrium has been recognized for 30 years, but despite considerable research effort, the in vivo role of uterine natural killer (uNK) cells in both normal and pathological pregnancy remains uncertain. uNK cells may differentiate from precursors present in endometrium, but migration from peripheral blood in response to chemokine stimuli with in situ modification to a uNK cell phenotype is also possible. uNK cells produce a wide range of secretory products with diverse effects on trophoblast and spiral arteries which may play an important role in implantation and early placentation. Interactions with other decidual cell populations are also becoming clear. Recent evidence has demonstrated subpopulations of uNK cells and the presence of other innate lymphoid cell populations in decidua which may refine future approaches to investigation of the role of uNK cells in human pregnancy.

Single-cell reconstruction of the early maternal-fetal interface in humans.

During early human pregnancy the uterine mucosa transforms into the decidua, into which the fetal placenta implants and where placental trophoblast cells intermingle and communicate with maternal cells. Trophoblast-decidual interactions underlie common diseases of pregnancy, including pre-eclampsia and stillbirth. Here we profile the transcriptomes of about 70,000 single cells from first-trimester placentas with matched maternal blood and decidual cells. The cellular composition of human decidua reveals subsets of perivascular and stromal cells that are located in distinct decidual layers. There are three major subsets of decidual natural killer cells that have distinctive immunomodulatory and chemokine profiles. We develop a repository of ligand-receptor complexes and a statistical tool to predict the cell-type specificity of cell-cell communication via these molecular interactions. Our data identify many regulatory interactions that prevent harmful innate or adaptive immune responses in this environment. Our single-cell atlas of the maternal-fetal interface reveals the cellular organization of the decidua and placenta, and the interactions that are critical for placentation and reproductive success.

Endometrial vascular development in heavy menstrual bleeding: altered spatio-temporal expression of endothelial cell markers and extracellular matrix components.

STUDY QUESTION: Are there any phenotypic and structural/architectural changes in the vessels of endometrium and superficial myometrium during the normal menstrual cycle in healthy women and those with heavy menstrual bleeding (HMB)? SUMMARY ANSWER: Spatial and temporal differences in protein levels of endothelial cell (EC) markers and components of the extracellular matrix (ECM) were detected across the menstrual cycle in healthy women and these are altered in HMB. WHAT IS KNOWN ALREADY: HMB affects 30% of women of reproductive age with ~50% of cases being idiopathic. We have previously shown that the differentiation status of endometrial vascular smooth muscle cells (VSMCs) is altered in women with HMB, suggesting altered vessel maturation compared to controls. Endometrial arteriogenesis requires the co-ordinated maturation not only of the VSMCs but also the underlying ECs and surrounding ECM. We hypothesized that there are spatial and temporal patterns of protein expression of EC markers and vascular ECM components in the endometrium across the menstrual cycle, which are altered in women with HMB. STUDY DESIGN, SIZE, DURATION: Biopsies containing endometrium and superficial myometrium were taken from hysterectomy specimens from both healthy control women without endometrial pathology and women with subjective HMB in the proliferative (PP), early secretory (ESP), mid secretory (MSP) and late secretory (LSP) phases (N = 5 for each cycle phase and subject group). Samples were fixed in formalin and embedded in paraffin wax. PARTICIPANTS/MATERIALS, SETTING, METHODS: Serial sections (3µm thick) were immunostained for EC markers (factor VIII related antigen (F8RA), CD34, CD31 and ulex europaeus-agglutinin I (UEA-1) lectin), structural ECM markers (osteopontin, laminin, fibronectin and collagen IV) and for Ki67 to assess proliferation. Immunoreactivity of vessels in superficial myometrium, endometrial stratum basalis, stratum functionalis and luminal region was scored using either a modified Quickscore or by counting the number of positive vessels. MAIN RESULTS AND THE ROLE OF CHANCE: In control samples, all four EC markers showed a dynamic expression pattern according to the menstrual cycle phase, in both endometrial and myometrial vessels. EC protein marker expression was altered in women with HMB compared with controls, especially in the secretory phase in the endometrial luminal region and stratum functionalis. For example, in the LSP expression of UEA-1 and CD31 in the luminal region decreased in HMB (mean quickscore: 1 and 5, respectively) compared with controls (3.2 and 7.4, respectively) (both P = 0.008), while expression of F8RA and CD34 increased in HMB (1.4 and 8, respectively) compared with controls (0 and 5.8, respectively) (both P = 0.008). There was also a distinct pattern of expression of the vascular structural ECM protein components osteopontin, laminin, fibronectin and collagen IV in the superficial myometrium, stratum functionalis and stratum basalis during the menstrual cycle, which was altered in HMB. In particular, compared with controls, osteopontin expression in HMB was higher in stratum functionalis in the LSP (7.2 and 11.2, respectively P = 0.008), while collagen IV expression was reduced in stratum basalis in the MSP (4.6 and 2.8, respectively P = 0.002) and in stratum functionalis in the ESP (7 and 3.2, respectively P = 0.008). LIMITATIONS, REASONS FOR CAUTION: The protein expression of vascular EC markers and ECM components was assessed using a semi-quantitative approach in both straight and spiral arterioles. In our hospital, HMB is determined by subjective criteria and levels of blood loss were not assessed. WIDER IMPLICATIONS OF THE FINDINGS: Variation in the protein expression pattern between the four EC markers highlights the importance of choice of EC marker for investigation of endometrial vessels. Differences in expression of the different EC markers may reflect developmental stage dependent expression of EC markers in endometrial vessels, and their altered expression in HMB may reflect dysregulated vascular development. This hypothesis is supported by altered expression of ECM proteins within endometrial vessel walls, as well as our previous data showing a dysregulation in VSMC contractile protein expression in the endometrium of women with HMB. Taken together, these data support the suggestion that HMB symptoms are associated with weaker vascular structures, particularly in the LSP of the menstrual cycle, which may lead to increased and extended blood flow during menstruation. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by Wellbeing of Women (RG1342) and Newcastle University. There are no competing interests to declare. TRIAL REGISTRATION NUMBER: Not applicable.

IFPA meeting 2017 workshop report: Clinical placentology, 3D structure-based modeling of placental function, placental bed, and treating placental dysfunction.

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2017 there were four themed workshops, all of which are summarized in this report. These workshops discussed new knowledge and technological innovations in the following areas of research: 1) placental bed; 2) 3D structural modeling; 3) clinical placentology; 4) treatment of placental dysfunction.

Standardisation of uterine natural killer (uNK) cell measurements in the endometrium of women with recurrent reproductive failure.

Considerable work is being carried out on endometrial NK cells to determine whether they play a role in successful pregnancy outcome. In addition there is debate about whether measurements of uNK should be included in the clinical assessment for women with recurrent implantation failure or recurrent miscarriage. A hindrance to taking this forward is the fact that the density of uNK cells reported by different centres is very different. The aim of this study was to determine the reason for these differences and to develop a standardised method. Three centres participated in the study. Each centre exchanged five formalin fixed, wax embedded sections of endometrium from five women. Sections were immunostained for CD56. Images were taken of 10 random fields at ×400 magnification; total stromal and uNK cells were counted using Image J. Results were expressed as % positive uNK cells and the variation in counts obtained in each centre was compared. After initial analysis a standardised protocol was agreed and the process repeated. Significant variation was seen in the counts obtained after initial analysis (Centre A vs.B, mean difference=-0.72 P<0.001; A vs.C mean difference=-0.47 P<0.001; B vs.C, mean difference=0.25 P=0.085). Analysis suggested that differences may be due to duration of tissue fixation, the embedding and sectioning processes, selection of areas for assessment, definition of immunopositive cells and inclusion or exclusion of blood vessels. Adoption of a standardised protocol reduced the variation (Centre A vs.B mean difference=-0.105 P=0.744; A vs.C mean difference=0.219 P=0.150; B vs.C mean difference=0.32 P=0.031). Use of a standardised method is needed to establish a normal range for uNK cells and to develop a meaningful clinical test for uNK cell measurements.

Decidual macrophages: key regulators of vascular remodeling in human pregnancy.

Successful remodeling of the uterine spiral arteries is essential for a complication-free pregnancy and is best described in terms of its morphologic features. The molecular mediators and cellular sources of spiral artery remodeling are not known, although a role for uterine leukocytes has been proposed. Immunohistochemical assessment of placental bed biopsies demonstrated uterine NK cells, macrophages, and T lymphocytes in the wall and adventitia of spiral arteries at different stages of remodeling, regardless of the presence of extravillous trophoblast cells. Leukocytes were more prevalent in vessel adventitia than wall, and macrophages were the most abundant leukocyte population. Macrophages, separated from early pregnancy decidua, did not alter extravillous trophoblast cells invasion or vascular smooth muscle cell organization or differentiation status but did induce extracellular matrix breakdown (reduced immunostaining of laminin, P = 0.05; fibronectin, P = 0.02) and were able to phagocytose apoptotic vascular smooth muscle cells. Decidual macrophages were shown to secrete a wide range of cytokines (IL-1ß, -2, -4, -5, -6, -8, -10, and -13 and TNF-α), proteases (matrix metalloproteinase-1, -2, -7, -9, and -10), and angiogenic growth factors (angiogenin, keratinocyte growth factor, fibroblast growth factor B, vascular endothelial growth factor A, and angiopoietin-1 and -2). We conclude that spiral artery remodeling involves the coordinated activity of a range of cell types, including extravillous trophoblast cells, decidual uterine NK cells, and macrophages in a carefully, spatiotemporally regulated manner.

Pathophysiology of heavy menstrual bleeding.

Heavy menstrual bleeding (HMB) is a common gynecological complaint with multiple etiologies and diverse pathophysiological origins. This review discusses HMB with reference to the recently proposed PALM-COEIN classification system for abnormal uterine bleeding, initially describing the endometrial events in normal menstruation followed by discussion of the perturbations of normal endometrial shedding that can result in HMB. Our present understanding of the mechanisms of menstrual bleeding as well as many of the pathological aberrations of HMB is incomplete. Further research into the pathophysiology of HMB is urgently needed, as clear knowledge of the mechanisms of this disorder will provide new therapeutic targets to formulate more effective treatments.

Menstrual cycle distribution of uterine natural killer cells is altered in heavy menstrual bleeding.

Heavy menstrual bleeding (HMB) affects 30% of women of reproductive age and significantly interferes with quality of life. Altered endometrial vascular maturation has been reported in HMB and recurrent miscarriage, the latter associated with increased uterine natural killer (uNK) cell numbers. This study compared endometrial leukocyte populations in controls and women with HMB. Formalin-fixed paraffin-embedded endometrial biopsies from controls (without endometrial pathology) and HMB were immunostained for CD14 (macrophages), CD56 (uNK cells), CD83 (dendritic cells), FOXP3 (regulatory T cells/Tregs), CD3 and CD8 (T cells). Leukocyte numbers were analysed as a percentage of total stromal cells in five randomly selected fields of view in the stratum functionalis of each sample. In control women across the menstrual cycle, 2-8% of total stromal cells were CD3(+) cells, 2-4% were CD8(+) T cells and 6-8% were CD14(+) macrophages. Compared with controls, CD3(+) cells were reduced during the mid-secretory phase (4%, P<0.01) and increased in the late secretory phase (12%, P=0.01) in HMB. CD83(+) dendritic cells and FOXP3(+) Tregs were scarce throughout the menstrual cycle in both groups. In controls, 2% of stromal cells in proliferative endometrium were CD56(+) uNK cells, increasing to 17% during the late secretory phase. In HMB, CD56(+) uNK cells were increased in the proliferative (5%, P<0.01) and early secretory (4%, P<0.02) phases, but reduced (10%, P<0.01) in the late secretory phase. This study demonstrates dysregulation of uNK cells in HMB, the functional consequence of which may have an impact on endometrial vascular development and/or endometrial preparation for menstruation.

The Role of Uterine NK Cells in Normal Reproduction and Reproductive Disorders.

The human endometrium contains a substantial population of leucocytes which vary in distribution during the menstrual cycle and pregnancy. An unusual population of natural killer (NK) cells, termed uterine NK (uNK) cells, are the most abundant of these cells in early pregnancy. The increase in number of uNK cells in the mid-secretory phase of the cycle with further increases in early pregnancy has focused attention on the role of uNK cells in early pregnancy. Despite many studies, the in vivo role of these cells is uncertain. This chapter reviews current information regarding the role of uNK cells in healthy human pregnancy and evidence indicating their importance in various reproductive and pregnancy problems. Studies in humans are limited by the availability of suitable tissues and the limitations of extrapolation from animal models.

Inflammatory Signalling in Fetal Membranes: Increased Expression Levels of TLR 1 in the Presence of Preterm Histological Chorioamnionitis.

Histological chorioamnionitis (HCA) is an established marker of ascending infection, a major cause of preterm birth. No studies have characterised the global change in expression of genes involved in the toll-like receptor (TLR) signalling pathways in the presence of HCA in the setting of preterm birth (pHCA). Fetal membranes were collected immediately after delivery and underwent histological staging for inflammation to derive 3 groups; term spontaneous labour without HCA (n = 9), preterm birth <34 weeks gestation without HCA (n = 8) and pHCA <34 weeks (n = 12). Profiling arrays ran in triplicate for each group were used to determine the expression of 84 genes associated with TLR signalling and screen for genes of interest (fold change >2; p<0.1). Expression of identified genes was validated individually for all samples, relative to GAPDH, using RT-PCR. Expression of TLR 1, TLR 2, lymphocyte antigen 96, interleukin 8 and Interleukin-1 receptor-associated kinase-like 2 was increased in pHCA (p<0.05). Degree of expression was positively associated with histological staging of both maternal and fetal inflammation (p<0.05). The inflammatory expression profile at the maternal/fetal interface associated with pHCA, a reflection of ascending infection, is extremely heterogeneous suggesting polymicrobial involvement with activation of a common pathway. Antagonism of TLR 1 and TLR 2 signalling in this setting warrants further assessment.

Altered vascular smooth muscle cell differentiation in the endometrial vasculature in menorrhagia.

STUDY QUESTION: How does the smooth muscle content and differentiation stage of vascular smooth muscle cells (VSMCs) in endometrial blood vessels change according to the different phases of the menstrual cycle and is this altered in women with menorrhagia? SUMMARY ANSWER: The smooth muscle content (as a proportion of the vascular cross-sectional area) of endometrial blood vessels remained unchanged during the normal menstrual cycle and in menorrhagia; however, expression of the VSMC differentiation markers, smoothelin and calponin, was dysregulated in endometrial blood vessels in samples from women with menorrhagia compared with controls. WHAT IS KNOWN ALREADY: Menorrhagia affects 30% of women of reproductive age and is the leading indication for hysterectomy. Previous studies have suggested important structural and functional roles for endometrial blood vessels, including impaired vascular contractility. Differentiation of VSMC from a synthetic to contractile state is associated with altered cellular phenotype that contributes to normal blood flow and pressure. This vascular maturation process has been little studied in endometrium both across the normal menstrual cycle and in menorrhagia. STUDY DESIGN, SIZE, DURATION: Endometrial biopsies were taken from hysterectomy specimens or by pipelle biopsy prior to hysterectomy in controls without endometrial pathology and in women with menorrhagia (n = 7 for each of proliferative, early-secretory, mid-secretory and late-secretory phases for both groups). Biopsies were formalin fixed and embedded in paraffin wax. PARTICIPANTS/MATERIALS, SETTING, METHODS: Paraffin-embedded sections were immunostained for α smooth muscle actin (αSMA), myosin heavy chain (MyHC), H-caldesmon, desmin, smoothelin and calponin (h1 or basic). VSMC content was measured in 25 αSMA(+) vascular cross sections per sample and expressed as a ratio of the muscular area:gross vascular cross-sectional area. VSMC differentiation was analysed by the presence/absence of differentiation markers compared with αSMA expression. Smoothelin and calponin expression was also analysed in relation to total number of blood vessels by double immunostaining for endothelial cell markers. MAIN RESULTS AND THE ROLE OF CHANCE: Study of VSMC differentiation markers revealed decreased expression of calponin both in αSMA(+) vessels (P = 0.008) and in relation to total number of vessels (P = 0.001) in late secretory phase endometrium in menorrhagia compared with controls. Smoothelin expression in αSMA(+) vessels was increased (P = 0.03) in menorrhagia, although this was not significant in relation to the total number of vessels. In normal endometrium, the proportion of blood vessels expressing αSMA increased from 63% in proliferative endometrium to 81% in the late secretory phase (P = 0.002). The overall arterial muscle content did not differ between control and menorrhagia at any phase of the menstrual cycle, occupying 78-81% of gross vascular cross-sectional area during the different menstrual cycle phases. LIMITATIONS, REASONS FOR CAUTION: This study included both straight and spiral arterioles and analysed only stratum functionalis. The VSMC differentiation with respect to αSMA expression is an observational study and the data are presented as presence or absence of the differentiation markers in each field of view, corresponding with the vascular cross sections included in the study of vascular muscle content. WIDER IMPLICATIONS OF THE FINDINGS: Smoothelin and calponin have been widely implicated as important regulators of vascular tone, vascular contractility and rate of blood flow. Our results have uncovered a disparate pattern of calponin expression, potentially indicating a dysfunctional contraction mechanism in the endometrial blood vessels in menorrhagia, thus implicating calponin as a potential therapeutic target. STUDY FUNDING/COMPETING INTERESTS: This study was funded by Wellbeing of Women (RG1342) and Newcastle University. There are no competing interests to declare. TRIAL REGISTRATION NUMBER: Not applicable.

Spiral artery remodeling and trophoblast invasion in preeclampsia and fetal growth restriction: relationship to clinical outcome.

Failure to transform uteroplacental spiral arteries is thought to underpin disorders of pregnancy, including preeclampsia and fetal growth restriction (FGR). In this study, spiral artery remodeling and extravillous-cytotrophoblast were examined in placental bed biopsies from normal pregnancy (n = 25), preeclampsia (n = 22), and severe FGR (n = 10) and then compared with clinical parameters. Biopsies were immunostained to determine vessel wall integrity, extravillous-cytotrophoblast location/density, periarterial fibrinoid, and endothelium. Muscle disruption was reduced in myometrial spiral arteries in preeclampsia (P = 0.0001) and FGR (P = 0.0001) compared with controls. Myometrial vessels from cases with birth weight <5th percentile (P<0.001), abnormal uterine Doppler (P<0.01), abnormal umbilical artery Doppler (P<0.001), and preterm delivery (P<0.001) had less muscle destruction compared with >5th percentile. Fewer extravillous-cytotrophoblast surrounded both decidual and myometrial vessels in the normal group and preeclampsia group compared with the FGR group (P = 0.001). For myometrial vessels, the normal group contained more intramural extravillous-cytotrophoblast than in preeclampsia (P = 0.015). Decidual vessels in the FGR group had less fibrinoid deposition compared with controls (P = 0.013). For myometrial vessels, less fibrinoid was deposited in both the preeclampsia group (P = 0.0001) and the FGR group (P = 0.01) when compared with controls, and less fibrinoid was deposited in the preeclampsia group when compared with FGR group (P<0.001). Myometrial vessels obtained from birth weights <5th percentile had less periarterial fibrinoid than those with >5th percentile (P<0.02). A major defect in myometrial spiral artery remodeling occurs in preeclampsia and FGR that is linked to clinical parameters. Interstitial extravillous-cytotrophoblast is not reduced in preeclampsia but is increased in FGR.

Altered expression of interleukin-6, interleukin-8 and their receptors in decidua of women with sporadic miscarriage.

STUDY QUESTION: Are alterations in decidual expression of interleukin (IL)-6 and IL-8 associated with sporadic miscarriage? SUMMARY ANSWER: IL-6 and IL-8 secretion from decidual uterine natural killer (uNK) cells and macrophages isolated from women with spontaneous miscarriage was reduced compared with normal controls. WHAT IS KNOWN ALREADY: Miscarriage is a common gynaecological problem with huge financial and personal implications. Eleven to twenty per cent of all clinically recognized pregnancies are lost before the 20th week of gestation, with miscarriages often being divided into early (≤ 12 completed weeks from last menstrual period) and late (≥ 13 weeks). Spiral artery remodelling is a key feature of early pregnancy; failure of this process has been implicated in sporadic miscarriage. The molecular triggers that initiate spiral artery remodelling are not clear, although cytokines such as IL-6 and IL-8 may play a role. STUDY DESIGN, SIZE, DURATION: This was a laboratory-based study using decidual and placental bed biopsy samples from women with sporadic miscarriage (n = 30) and termination of pregnancy controls (n = 30). PARTICIPANTS/MATERIALS, SETTING, METHODS: Total adherent decidual cells, CD10(+) stromal cells, CD14(+) macrophages and CD56(+) uNK cells were isolated from decidua from apparently normal pregnancies that were terminated at either 8-10 or 12-14 weeks' gestation. In addition, CD14(+) macrophages and CD56(+) uNK cells were isolated from decidua from sporadic miscarriage at 8-10 weeks' gestation. Secreted IL-8 was measured in all isolated cell populations, while IL-6 was measured in CD14(+) macrophages and CD56(+) uNK cells from both sporadic miscarriage and normal controls. Placental bed biopsies were taken from women after sporadic miscarriage or termination of pregnancy at ≤ 12 completed weeks' or >13 weeks' gestational age, formalin-fixed, paraffin-embedded and immunostained for IL-6, IL-6Rα, GP130, IL-8, CXCR1, CXCR2 and CD13 (aminopeptidase N). Staining intensity for each factor was assessed in extravillous trophoblast cell populations, myometrial and decidual stroma, myometrial and decidual spiral arteries and decidual glandular epithelium. A CPA model was used to assess the potential role of IL-6 and IL-8 in spiral artery remodelling. MAIN RESULTS AND THE ROLE OF CHANCE: IL-8 was secreted by total adherent decidual cells, CD10(+) stromal cells and CD14(+) macrophages at both 8-10 and 12-14 weeks' gestation, with CD14(+) cells secreting the highest levels. Both CD14(+) and CD56(+) cells isolated from decidua of early sporadic miscarriage produced lower IL-6 (P = 0.04, P = 0.01, respectively) and IL-8 levels (P = 0.0007, P = 0.002, respectively) compared with normal cases. In addition, altered expression of IL-6, IL-8 and their receptors was observed in various cell types in placental bed (myometrial stroma, glandular epithelium, interstitial extravillous trophoblast cells, vascular smooth muscle cells and endothelial cells) in sporadic miscarriage, particularly from later gestational ages. IL-6 and IL-8 disrupted vascular smooth muscle morphology and organization in an in vitro model of spiral artery remodelling. LIMITATIONS, REASONS FOR CAUTION: By the nature of sampling at the time of miscarriage, it was not possible to ascertain the cause or effect in the observed alterations of levels of IL-6 and IL-8 in sporadic miscarriage. WIDER IMPLICATIONS OF THE FINDINGS: Alterations in the expression of IL-6, IL-8 and their receptors may be associated with the aetiology of sporadic miscarriage, especially given the potential role of these cytokines in the regulation of trophoblast invasion and spiral artery remodelling. STUDY FUNDING/COMPETING INTEREST(S): This project was supported by funding from Wellbeing of Women (RG1000). The authors have no competing interests to declare. TRIAL REGISTRATION NUMBER: Not applicable.

Corin, an enzyme with a putative role in spiral artery remodeling, is up-regulated in late secretory endometrium and first trimester decidua.

STUDY QUESTION: What is the nature of cellular Corin expression in human gestational tissues? SUMMARY ANSWER: CORIN is expressed in non-pregnant late secretory phase endometrium, first trimester human implantation sites and is up-regulated with decidualization ex vivo. WHAT IS KNOWN ALREADY: Adequate trophoblast invasion and spiral artery remodeling/transformation is critical for successful implantation. CORIN, best known for its role in activating atrial natruietic peptide (ANP) to regulate blood pressure, has recently been proposed to be centrally involved in trophoblast invasion and spiral artery remodeling. It is postulated that ANP, activated by CORIN, promotes trophoblast invasion and that a deficiency causes pre-eclampsia. Mice deficient in either Corin or ANP displayed poor trophoblast invasion, impaired spiral artery remodeling and phenocopied human pre-eclampsia. However, the precise cellular localization of CORIN within human gestational tissues has not been well characterized. STUDY DESIGN, SIZE, DURATION: We measured CORIN protein localization in a number of human gestational tissues relevant to early embryo/placental implantation: non-pregnant (NP) endometrial biopsies (n = 5 per phase of the menstrual cycle), first trimester placental bed biopsies (n = 12) and pre-term control (n = 10) and severe early onset preeclamptic placentas (n = 15). Endometrial stromal cells were isolated from human endometrial biopsies (n = 5) and induced to decidualize ex vivo. Finally, CORIN concentrations were measured in serum obtained from pregnant women during the first trimester of whom, 56 subsequently ended up with a healthy term delivery (controls), 18 developed fetal growth restriction (FGR) and 21 had a miscarriage. PARTICIPANTS/MATERIALS, SETTING, METHODS: We performed immunohistochemistry to assess CORIN localization. Changes in Corin mRNA expression in human endometrial stromal cells decidualized ex vivo were measured by quantitative RT-PCR, and levels of CORIN within human sera were measured by ELISA. MAIN RESULTS AND THE ROLE OF CHANCE: CORIN was expressed in both NP late secretory phase endometrium and first trimester decidua within placental bed biopsies. Importantly, decidualization of primary human endometrial cells ex vivo significantly increased Corin expression (P < 0.05). CORIN was also detected within the villous cytotrophoblast, but there was no change in mRNA levels in placentas complicated by severe preterm pre-eclampsia when compared with pre-term controls. Although CORIN was detected in first trimester serum, levels did not change across gestation, nor could they predict miscarriage or FGR (other disorders of impaired placental invasion). LIMITATIONS, REASONS FOR CAUTION: Owing to the fact that we utilized early pregnancy human specimens, this is mainly a descriptive study with a limited amount of functional experiments. WIDER IMPLICATIONS OF THE FINDINGS: This is the first study to thoroughly characterize Corin mRNA and protein expression in human gestational tissue. Our findings support recent data from murine studies collectively suggesting that CORIN plays a critical role in trophoblast migration and spiral artery remodeling during early pregnancy in humans. Therefore, further studies of CORIN biology in early pregnancy may identify new therapeutic targets to improve implantation quality in early pregnancy and potentially reduce the rates of pregnancy complications caused by inadequate implantation (pre-eclampsia, FGR and miscarriage). STUDY FUNDING/COMPETING INTEREST(S): This study was supported by The National Health and Medical Research Council of Australia (Salary support #490970, #490995). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. The authors declare that no competing interests exist.

Uterine natural killer cells initiate spiral artery remodeling in human pregnancy.

Uterine spiral artery remodeling is required for successful human pregnancy; impaired remodeling is associated with pregnancy complications, including late miscarriage, preeclampsia, and fetal growth restriction. The molecular triggers of remodeling are not known, but it is now clear that there are "trophoblast-independent" and "trophoblast-dependent" stages. Uterine natural killer (uNK) cells are abundant in decidualized endometrium in early pregnancy; they surround spiral arteries and secrete a range of angiogenic growth factors. We hypothesized that uNK cells mediate the initial stages of spiral artery remodeling. uNK cells and extravillous trophoblast (EVT) cells were isolated from early pregnancy decidua and placenta. Chorionic plate arteries from full-term placentas and spiral arteries from nonpregnant myometrium were cultured with angiogenic growth factors or conditioned medium (CM) from uNK cells or EVT or uNK cell/EVT cocultures. In both vessel models, uNK cell CM induced disruption of vascular smooth muscle cells (VSMCs) and breakdown of extracellular matrix components. Angiopoietin (Ang)-1, Ang-2, interferon-γ, and VEGF-C also disrupted VSMC integrity with an Ang-2 inhibitor abrogating the effect of uNK cell CM. These results provide compelling evidence that uNK cells contribute to the early stages of spiral artery remodeling; failure of this process could contribute to pregnancy pathology.